Extraction of succinic acid by aqueous two-phase system using alcohols/salts and ionic liquids/salts

• We extracted succinic acid was extracted with OmimBr/(NH4)2SO4 ATPS system.
• Extraction of succinic acid with ATPS using aqueous alcohols was controlled by pH.
• Extracted succinic acid was recovered as precipitation of sodium succinate.

Succinic acid is the important feedstock for several industrial products including biodegradable plastics. Production of a fermentation-derived succinic acid (bio-succinic acid) has recently emerged as a potential green technology. For bio-succinic acid production, 50–60% of processing costs are attributed to recovery and purification processes. In this paper, we examine aqueous two phase systems (ATPS) using water-miscible alcohols/salts and ionic liquids/salts to extract succinic acid. From binodal curves, the phase separation abilities of solvents are in the order t-butanol > 1-propanol > HmimBr > 2-propanol ≈ OmimBr > BmimBr > ethanol. Extractability of succinic acid was within 0–72.1% in ATPSs with 1-propanol using salt concentration of 20 g/100 mL-water and depended on the pH of the salt solution. When salts, K2HPO4, K3PO4, K2CO3, KF, (NH4)2SO4, C6H5Na3O7, Na2CO3, NaCl, MgSO4, and NH4NO3, were used, relatively high extractabilities were obtained by using the salt solutions which gave pH smaller than pKa1 of succinic acid. In the ATPS with ionic liquids, extractability of succinic acid was within 16–85.5% and were affected by not pH but the salts used. An ATPS with an OmimBr and (NH4)2SO4 system gave highest extraction, 85.5%. Extracted succinic acid was quantitatively precipitated by adding sodium hydroxide to the extracted phase and recovered as crystallization of sodium succinate.